The present invention relates to an underground soil pollution monitoring system for monitoring the integrity of underground fuel storage tanks.
Numerous attempts have been made to monitor underground pollution caused by leaks in tanks, pipelines or other containers of hazardous chemicals. A number of detection systems have been proposed such as in Murray U.S. Pat. No. 3,995,472 wherein a pair of insulated conductors adjacent a buried pipeline detect leakage by degradation of the insulation for the electrical conductors. A short circuit of the conductors will occur when the insulation is degraded. Thus, in this system two insulated conductors are required throughout the length of the sensor which, of course, is expensive. Moreover, should a break exist in one of the sensors, between a leak and the monitor, the system would be ineffective to detect a leakage. More recently, Klein disclosed in U.S. Pat. No. 4,305,068 an enclosure about a tank or pipe wherein the enclosure is filled with a liquid and two electrodes are placed in the enclosure in contact with the liquid. When leakage occurs in the presence of the container, the container degrades and the level of fluid inside the tube falls thereby breaking a circuit between the electrodes.
Other leakage detection systems have been developed which use an electrical grid network for locating leaks, such as described in Johnson U.S. Pat. No. 4,404,516.
None of these prior art devices have been capable of detecting low level, long term leakage of fuel in an underground environment in a safe reliable manner. Accordingly, it is an object of invention to provide an improved soil pollution monitoring system.